PURIFICATION, CRYSTALLIZATION AND PRELIMINARY-X-RAY DIFFRACTION STUDIES OF THE BACTERIOPHAGE-PHI-29 CONNECTOR PARTICLE

The connector or portal particle from double-stranded DNA bacteriophag e phi 29 has been crystallized, This structure, which connects the hea d of the virus with the tail and plays a central role in prohead assem bly and DNA packaging and translocation, is formed by 12 subunits of t he p10 protein and has a molecular weight of 430 kDa, The connector st ructure was proteolysed with endoproteinase Glu-C from Staphylococcus aureus V8, which removes 13 and 18 amino acids from the amino- and car boxy-terminal regions of the p10 protein, respectively, Two crystal fo rms were grown from drops containing an alcohol solution and paraffin oil. Crystals of form I are monoclinic, space group C2 with cell dimen sions a = 416.86 Angstrom, b = 227.62 Angstrom, 236.68 Angstrom and be ta = 96.3 degrees and contain four connector particles per asymmetric unit. Crystals of form II are tetragonal, space group P4(2)2(1)2 with cell dimensions a = b = 170.2 Angstrom, c = 156.9 Angstrom and contain half a particle per asymmetric unit. X-ray diffraction data from both native crystal forms have been collected to 6.0 and 3.2 Angstrom resp ectively using synchrotron radiation. Crystals of form II are likely t o have the same packing arrangement as the two-dimensional crystals an alyzed previously by electron microscopy. (C) 1998 Federation of Europ ean Biochemical Societies.